The type of engine which powered the A-300-600 airliner that crashed in New York has been hit by a series of "dramatic" failures.

The General Electric CF6 has disintegrated more than half a dozen times in the past two years, aviation analysts said. On previous occasions, however, the plane has landed safely, according to Kieran Daly of the aviation consultancy Air Transport Intelligence.

However, the experts were puzzled yesterday by the fact that, according to witnesses, one of the American Airlines plane's two engines became detached from the aircraft before it crashed, which had not happened previously.

On 18 May this year, a CF6 on a Monarch Airlines A-300-600 en route from Gatwick to Gambia failed at cruising height over Portugal.

Phil Butterworth-Hayes, civil aviation editor of Jane's Information Group, said the crash was far more likely to have been due to a mechanical or maintenance failure than to a terrorist attack.

He said the crash of the twin-engined aircraft could just as easily have been a "terrible coincidence" and that the event only gained sinister connotations from its proximity to the World Trade Centre. Crash records showed aircraft accidents to happen in "geographical and time-line clusters", so this crash could merely be following that inexplicable pattern.

According to Mr Butterworth-Hayes, the crash of American Airlines flight 587 might have been a catastrophic engine or systems failure, possibly caused through a disastrous fuel leak or by engine blades breaking. He said that this would have had to be massive, with more than three systems failures, for the fault to be irretrievable. He said: "Engines have been known to fall off aircraft and sometimes a plane can recover while other times it cannot, but these planes are built to withstand shut-down and up to two or three system failures."

He said the source of the problem may have occurred near the wings. "The way the engine is attached to the wing means it is the most vulnerable area of the aircraft. It's a very narrow area, and if there is a failure there, you lose three main power sources," he said.

While engine failure was common, it is very rare for it to be catastrophic, he said. Pilots at 36,000 feet can often rectify an engine problem but if it occurred at a lift-off position, they would not have the height or the time to recover. For this reason the plane, which was still climbing, would have been at a major disadvantage. Mr Butterworth-Hayes said: "If a plane loses power, it can run on one engine but if it loses more than engine power or if there is an explosion that severs the hydraulic system, you cannot usually recover control."

Mr Butterworth-Hayes argued that reports of an "explosion in the sky" before the engine fell from the aircraft should be treated with caution as this had been a common observation by witnesses to previous air disasters that was not necessarily found to be accurate. "Exploding aircraft are extremely rare. [But describing this] seems to be an extraordinarily popular psychological response to witnessing a crash."